Aerodynamic Control by Vorticity Transport Modification using Distributed Active Bleed

摘要

A scalable approach to aero-effected flight control using distributedactive surface bleed is investigated in wind tunnel experiments.Aerodynamic control is achieved over a wide range of pre- and post-stallangles of attack by large-area surface bleed of air that is driven by flightpressure differences flight and is regulated by low-power surfaceintegratedlouver valves. The interaction between the bleed and cross flowis tailored to leverage the generation and regulation of vorticityconcentrations near the surface to locally alter its apparent aerodynamicshape and thereby the aerodynamic loads. Low momentum quasi-steadyand time-periodic bleed leads to bi-directional deflections of the timeaveragedvorticity layer and effect significant increases or decreases in lift,drag, and pitching moment. High-speed PIV of the vorticity flux show thatthe bleed engenders trains of discrete vortices that advect along the surfaceand are associated with a local instability that is manifested by bifurcationof the time-averaged vorticity layer near the bleed outlets. The vorticesadvect over several convective times and alter the vorticity flux over theairfoil and thereby the aerodynamic loads. The present investigationsdemonstrate that active bleed can be implemented for direct lift control,maneuvering, or stabilization of flexible aerostructures.